Rollie Dad Method - Spindle alignment on my mini Lathe from Micromark 7x14

Using a Dial Test Indicator and instructions from http://www.gadgetbuilder.com/Lathe_Align.html to use Rollie Dad's Method to measure spindle & ways alignment on my 7x14 MicroMark Mini-Lathe

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[rowbare]

Nice video but you got the math wrong on the second reading. The method states: "Algebraically add (i.e. account for the signs) the minimum and maximum readings and divide by 2. The result is the vertical spindle axis error. "

That gives you 17 thou vs 3 thou error.

[saunixcomp]

@rowbare I misread the instructions (one reason why I like video examples versus text!). I interpreted the "add algebraically" as summing the positive 10 and negative 3. E.g. 10 + -7 = 3. Sounds like I need to add the (positive) movement in each direction - e.g. 10 + 7 = 17/2 = 8.5 tics which is 4.25 thousandth on my DTI. Sounds much more reasonable for an asian-import lathe...

[n5xrq]

Thanks for the video. You made the Rollie Dad Method look simple. I've seen references to it many times, but never tried it just because the written description seemed like too much trouble. I think I'll go give it a try!

[saunixcomp]

Thanks! However - I'm waiting for confirmation that my methodology (especially the math involved in the final DTI reading) is being done correctly.

[efzt]

I am not a machinist but can you adjust the spindle on a lathe? Are you trying to adjust the chuck jaws so they are centered ? I really need to get a lathe.

[FactoryDragon87]

Before the this test You hollow out by turning the chuck jaw??? No??? Bad=> it make error. Second is- NO ONE rod material is perfect round! Next is that- You NEVER turn so length rod piece without tailstock use- in this way can get hurt! Lathe accutacy can chech only then on this lathe turn! So, I think this is not correct way how test the lathe on accuracy.

[lPGlKarsten]

not a good test ....the part in the ....is it 100% perfekt and ...damn im german...

das teil in deiner maschiene,,,niemals 100% rund...und gerade ist es sicher auch nicht zu 100%

du kannst das so nicht messen kleiner 1!! iss lächerlich....

du hast zwar werte aber das sind nicht die , die du willst....

mfg

[Stantonleman]

The method in the video is correct. Algebraically summing means including the sign of the numbers when summing. Algebraic summing allows using a bent test bar with a constant diameter. This was the technique used to zero the DTI at the headstock. The resultant measurements 9" from the headstock are then added and divided by two to give 0.75 mil (0.00075") vertical misalignment. Aluminum foil shims on the prizm side of the headstock can bring that number < .005". The math is correct.

[gbowne1]

I use some big long dowel pins that are ground to 0.0002". You can also use Lathe mandrels taking care to note that the mandrels have a slight taper to them so you will have to account for that.